/*
 * Copyright (C) 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.util.concurrent;

/**
 * A simple ListenableFuture that holds a value or an exception.
 * 
 * @author Sven Mawson
 * @since 2009.09.15 <b>tentative</b>
 */
public class ValueFuture<V> extends AbstractListenableFuture<V> {

    /**
     * Creates a new {@code ValueFuture} in the default state.
     */
    public static <T> ValueFuture<T> create() {
        return new ValueFuture<T>();
    }

    /**
     * Explicit private constructor, use the {@link #create} factory method to
     * create instances of {@code ValueFuture}.
     */
    private ValueFuture() {
    }

    /**
     * Sets the value of this future. This method will return {@code true} if
     * the value was successfully set, or {@code false} if the future has
     * already been set or cancelled.
     * 
     * @param newValue
     *            the value the future should hold.
     * @return true if the value was successfully set.
     */
    @Override
    public boolean set(V newValue) {
        return super.set(newValue);
    }

    /**
     * Sets the future to having failed with the given exception. This exception
     * will be wrapped in an ExecutionException and thrown from the get methods.
     * This method will return {@code true} if the exception was successfully
     * set, or {@code false} if the future has already been set or cancelled.
     * 
     * @param t
     *            the exception the future should hold.
     * @return true if the exception was successfully set.
     */
    @Override
    public boolean setException(Throwable t) {
        return super.setException(t);
    }

    /**
     * {@inheritDoc}
     * 
     * <p>
     * A ValueFuture is never considered in the running state, so the
     * {@code mayInterruptIfRunning} argument is ignored.
     */
    @Override
    public boolean cancel(boolean mayInterruptIfRunning) {
        return super.cancel();
    }
}
